Hyperpredation as a mechanism responsible for the impact of introduced populations on native biodiversity

Species that have been introduced into regions outside their native range can damage biodiversity and natural ecosystems. Hyperpredation is the process by which an introduced primary prey enables a generalist predator to increase dramatically in numbers leading to sustained abnormally high predation of secondary native prey. Testing the hyperpredation model is a challenging task because it has several assumptions but no exclusive predictions that are inconsistent with alternative hypotheses, for which data supporting several predictions are required to validate this hypothesis. We reviewed studies that postulate hyperpredation as a mechanism explaining the impact of introduced species. We used Scopus and Google Scholar databases for finding publications and Prisma protocol for selecting them. No one of the 44 selected publications provided enough information to demonstrate hyperpredation as the mechanism responsible for the impact of introduced prey populations on native biodiversity because (i) in all studies there were other ecological mechanisms that could explain the observed decline of native prey; (ii) no study have considered all the assumptions of the hyperpredation model, nor found positive results for all its predictions, and (iii) most studies used observational, descriptive method instead of field experiments that explicitly try to refute alternative hypotheses.